Preheat oven to 350 degrees and prep a round 8" baking dish or pie dish by spraying with cooking spray or oil.
In a small sauté pan, heat olive oil on medium heat and sauté bell pepper, spinach and green onion for 3-4 mins. Transfer to a small bowl and allow to cool.
In a large bowl, add egg white, cottage cheese, monterey jack cheese, feta cheese, salt, and pepper. (If you're planning to use a tabletop blender, add these ingredients directly to a blender)
Using an immersion blender, blend for 30-60 seconds until fully combined and smooth. (If using a tabletop blender, blend on high until smooth)
Mix in cooled veggies.
Pour egg white quiche mixture into the baking dish and bake in the oven for 35-45 minutes. The quiche will be slightly browned and firm in the middle when finished.